Swimming pool covers for off-season use are available in two distinct varieties. One is a mesh construction, which lets rain and melting snow drain right through while providing safety and preventing large debris from entering the pool. The other type of pool cover is a solid vinyl safety cover, which is impervious to water. The solid vinyl covers are typically significantly heavier and therefore more difficult to roll or fold for removal. They also tend to drag on the pool decking and to catch on any irregularities.
The solid vinyl pool covers do have some advantages; they prevent most of the sunlight from penetrating thereby preventing the growth of some types of algae in the water below. They can also prevent the draining of contaminated water with fine debris and bacteria into the pool.
Actually, two types of solid vinyl pool covers are in common use. The type with centrally located drain panels, while not precluding contaminated water from entering the pool, still block UV rays from sunlight. The second type that is totally solid vinyl must be used with a weighted pump on the surface that automatically removes any standing water from the top surface; this prevents any contaminated water from entering the pool.
Existing swimming pool covers are usually either lightweight, open mesh covers, or heavy solid plastic or rubber pool covers, each having its own disadvantages.
For example, open mesh pool covers are lightweight, but since they have an open mesh, they allow rain and small organic particles to traverse the cover, thereby introducing excess rainwater or undesirable organic matter into the pool, requiring cleaning. On the other hand, solid pool covers are heavy to handle and remove.
What is lacking is a pool cover, which combines the lightweight feature of the mesh pool cover, while providing the impermeability of a solid pool cover.
Among related patent references include U.S. Patent Publication No. 2002/0116756 of Martin, which discloses a swimming pool cover comprised of a flexible fabric sheet having a mesh construction underside. However, the mesh is on the underside of the pool cover to reduce contact with the underside of the pool cover against the upper surface of the pool deck. Therefore, the mesh has to be distinctly three dimensional in the downward vertical direction, to isolate the solid upper pool cover fabric layer 24 away above the pool deck. As a result, the Martin cover is not like the thin dual ply pool cover of the present invention, with a mesh on the upper side, not the underside.
U.S. Pat. No. 4,122,561 of Barr discloses a pool cover of non-porous, flexible sheet material. Reinforced polyvinylchloride is preferred, wherein the reinforcing consists of mesh polyester cord between upper and lower layers of the polyvinylchloride.
U.S. Pat. No. 4,972,529 of Wolfson discloses a heavy duty protective blanket for pool covers having at least one intermediate layer of plastic mesh to provide structural integrity and durability. The upper UV resistant layer is described as being a polypropylene over the mesh, which is sandwiched between the upper layer and a lower polypropylene layer.
U.S. Pat. No. 5,920,922 of Ragsdale discloses a pool cover system wherein the cover is made from any suitable fabric including, preferably, a 16-ounce vinyl material reinforced with a strong polyester mesh to increase strength and tear resistance.
U.S. Pat. No. 5,546,615 of Chamness describes a pool cover of upper and lower sheets of 30 mil HDPE plastic surrounding a polystyrene insulation.
U.S. Pat. No. 4,262,373 of Chambers discloses a vinyl pool cover 41, which is reinforced with mesh.
U.S. Pat. No. 4,203,174 of Shults discloses a machine washable pool cover tarp 30 of laminar plastic, such as vinyl, which is reinforced with a tightly woven DACRON® mesh.
U.S. Pat. No. 3,762,983 of Osborn discloses a mesh material in general which is enclosed in a plastic film, such as low density polyethylene or a flexible ethylene copolymer. Unlike the prior patents which are mesh-reinforced upper and lower plastic films, in Osborn '983 the mesh itself is of strands having diameters of between 10-30 mils, preferably 12-24 mils, in thickness. The mesh strands are completely enclosed within the plastic film, as shown in FIG. 2, so that the mesh strands 13 are completely enclosed on all sides by the plastic film 12, making the overall thickness of the pool cover much thicker than the mesh strands themselves.
U.S. Pat. No. 3,593,757 of Haynes discloses a rip-resistant open weave woven pool cover.
Furthermore, U.S. Pat. No. 6,047,415 of Brown describes an algae-resistant pool cover, which floats on the pool water. Additionally, U.S. Pat. No. 4,708,080 of Conrad describes a woven material akin to a mesh, backed by a plastic laminate, such as, for example, MYLAR® or other plastics.